1. Field of the Invention
The present invention relates to a signal recording and reproducing apparatus and method for encoding and recording an input signal into a recording medium, and reproducing a signal from the recording medium.
2. Description of the Related Art
There have been proposed various encoding schemes for performing compression encoding of a digital signal, resulting from analogue-to-digital conversion of an analogue signal, such as an audio signal and a video signal, by utilizing statistical characteristics of the signal. These encoding schemes include lossless (reversible) encoding, which enables complete restoration of an encoded signal to a pre-encoded signal thereof, and lossy (non-reversible) encoding, which causes errors in restoration of an encoded signal.
In the case of lossless (reversible) encoding, it is possible to retain a high quality of a signal resulting from decoding and reproducing of an encoded signal, however, in general, the amount of encoded data is large; whereas, in the case of lossy (non-reversible) encoding, it is possible to reduce the amount of encoded data to a small amount, however, the quality of the reproduced signal is inferior to that in the case of lossless (reversible) encoding.
Moreover, in the related art, a voice encoding apparatus is disclosed in, for example, U.S. Patent Application Publication No. 2003/0171919, in which a non-reversible (lossy) compression of an input voice signal is performed to produce a core (base layer) stream, and a reversible (lossless) compression of a residual-error signal is performed to produce an enhanced (enhancement layer) stream, and further, these streams are combined into one stream; and thereby, scalability between lossy compression and lossless compression can be achieved. In a voice decoding apparatus disclosed therein, a lossy decoded voice signal can be produced by decoding the core stream, and additionally, a lossless decoded signal can be produced by decoding the core stream and the enhanced stream, and by arithmetic addition of both the resultant decoded streams.
Furthermore, the production and decoding of a scalable lossless stream as well as a reduction in the processing time spent in producing and decoding the lossless stream have been realized using a voice encoding apparatus and method thereof and a voice decoding apparatus and method thereof disclosed in Japanese Unexamined Patent Application Publication No. 2007-034230.